linux-kernel - [PATCH 2/2] ALSA: compress_offload: avoid 64-bit get

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Message-Id: <20241216093410.377112-2-arnd@kernel.org>
Date: Mon, 16 Dec 2024 10:33:41 +0100
From: Arnd Bergmann <arnd@...nel.org>
To: Vinod Koul <vkoul@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Amadeusz Sławiński <amadeuszx.slawinski@...ux.intel.com>
Cc: Arnd Bergmann <arnd@...db.de>,
	Yu Jiaoliang <yujiaoliang@...o.com>,
	Peter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
	linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] ALSA: compress_offload: avoid 64-bit get_user()

From: Arnd Bergmann <arnd@...db.de>

On some architectures, get_user() cannot read a 64-bit user variable:

arm-linux-gnueabi-ld: sound/core/compress_offload.o: in function `snd_compr_ioctl':
compress_offload.c:(.text.snd_compr_ioctl+0x538): undefined reference to `__get_user_bad'

Use an equivalent copy_from_user() instead.

Fixes: 04177158cf98 ("ALSA: compress_offload: introduce accel operation mode")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 sound/core/compress_offload.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
index ec2485c00e49..1d6769a66810 100644
--- a/sound/core/compress_offload.c
+++ b/sound/core/compress_offload.c
@@ -1180,9 +1180,9 @@ static int snd_compr_task_seq(struct snd_compr_stream *stream, unsigned long arg
 
 	if (stream->runtime->state != SNDRV_PCM_STATE_SETUP)
 		return -EPERM;
-	retval = get_user(seqno, (__u64 __user *)arg);
-	if (retval < 0)
-		return retval;
+	retval = copy_from_user(&seqno, (__u64 __user *)arg, sizeof(seqno));
+	if (retval)
+		return -EFAULT;
 	retval = 0;
 	if (seqno == 0) {
 		list_for_each_entry_reverse(task, &stream->runtime->tasks, list)
-- 
2.39.5